We have discovered the presence of tumor-associated antigens in bladder tumor cell membrane preparations, and have been succesful in separting and identifying these antigens. The tumor-associated antigens of bladder cancer of the transitional cell type appear to be common to all of the bladder cancers of this type, as we have tested both autologous and allogeneic delayed hypersensitive skin test reactions to all of the separated soluble antigens as well as to the crude membrane extracts in 14 bladder cancer and 14 breast cancer patients. Our results show that, in bladder cancer patients not anergic to recall antigens (SKSD - streptokinase:streptodornase, mumps, and candida), there are reactions only to the membrane preparations and to the specific soluble membrane antigens present in Sephadex fraction II of this material. Further separation and identification of the antigens involved was performed using our special method of a 4-stacked gel polyacrylamide electrophoresis. There are in squamous cell bladder carcinoma preparations herpesvirus-induced nonvirion antigens as well. Since July 1972 we have been cooperating in studies of the inhibition of lymphocyte cytotoxicity with extracts from fetal bladder, normal bladder and all of the separated soluble membrane antigens from the bladder tumors. We are doing side-by-side comparison of the skin test results and the ability of the extracts of inhibit killing by cytotoxic lymphocytes. We have discovered certain cancer antigens which inhibit and have also discovered a group of antigens which enhance. We plan to continue exploring simultaneously the inhibition and stimulation as well as the cytotoxic capacity of the stimulated cells. We plan a large scale evaluation of skin testing of the tumor-associated antigen with Dr. Miller, Dept. of Urology. We plan to use monospecific sera to the antigens and purified antigens for assays which include immunodiffusion, radioimmunoassay, complement-fixation and other tests. We thus anticipate a carefully limited spectrum of studies designed to test the clinical correlation of response to tumor-associated antigen and the study of the nature of the immune response, with a view to screening, diagnosis, follow-up and possible therapeutic applications.